How to blur your photo's background using Adobe Photoshop

Member

By Jin Li
User-Submitted Article

Article Rating: (15 Ratings)

photoshop background

Do you have a good picture but the background is not so pretty and you want to blur it out? If so, please look at this article. It will tell you exactly how to blur not so pretty backgrounds using photoshop.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

Adobe Photoshop CS2
a photo

Step 1

starting image

Open your photo in Adobe Photoshop CS2 and duplicate the original image by CTRL J. This is my starting image.
Step 2

channels in Adobe photoshop

If we want to selectively blur out the background, we need to create a mask. A mask is black and white only and will accomplish this easily. You will understand this later. For this image, it's relatively easy to create a mask. Let's look at the channels dialog box. This dialog box contains all the color information in RGB, red, green and blue channels.
Step 3

red channel in Adobe Photoshop

In my case, the red channel contains the greatest amount of contrast between the flower and background. So, we will duplicate this channel by right clicking on it and duplicate. We can not modify a channel directly as it contains color information of the image. If we modify it directly, it will mess up the image.
Step 4

levels in Adobe Photoshop

We still need to exaggerate the difference between flower and background. Go up to image, adjustment, and choose levels. Change the first value to 66, and the last value to 168.
Step 5

First mask in Adobe photoshop

Now, we need to use the dodge and burn brush to define nice edges. In other words, we want to make everything black and white at the edges with dodge and burn brush. For the dodge tool, set range to highlights and exposure to 50%. For the burn tool, set range to shadows and exposure to 50%. Then, you will need to make the background all black by using the polygonal lasso tool and fill with black. Please see the picture as what my mask looks like.
Step 6

You might notice something, I am missing the stem of the flower. Without the stem, the effect won't look as perfect. So, we need to add the stem to our mask. Let's look at the color channels again, none of the channels have much contrast between the stem and background. So, when in doubt, choose the green channel. Duplicate the green channel before making any modifications.
Step 7

levels in adobe photoshop

Go to image, adjustment and levels. Change the first value from 0 to 63 and change the last value from 255 to 99.
Step 8

second mask in Adobe photoshop

Use the dodge and burn tool to exaggerate the contrast between stem and background. Then, use the polygonal lasso tool to change everything else to black.
Step 9

calculations in Adobe Photoshop

Now, we need to use calculations to add the two mask together into our final mask. Go up to image and choose calculations. Source 1 = flower mask, Source 2 = stem mask that we just created. And change the blending to add. Tell Photoshop to create a new channel for the final mask.
Step 10

final mask in Adobe photoshop

Your final mask should look something like this.
Step 11

lens blur in Adobe photoshop

Now, go up to filter, blur and lens blur. Load your final mask in the depth mask's source, turn off inverse. If you have inverse on, then the flower will be blurred and background will remain in sharp focus. You can change the lens's shape base on your preference. The higher the radius value, the more blurry the background.
Step 12

final image in Adobe photoshop

Your final image should look something like this
Step 13

Click on the link below to learn more about photoshop.